BL9000 HS carburetor adjustment

Discussion in 'Lawn Mowing Equipment' started by crammit442, Jan 26, 2019.

  1. crammit442

    crammit442 LawnSite Member
    Messages: 115

    I've had my BL9000 blower for probably 1 1/2 years and while I haven't put the tach on it, I can hear a noticable drop in WOT rpm. Probably 2-300 rpm. Like everyone else, I normally just pull the tamper plug and adjust as needed. I went to do that today and after looking at the carb from every angle, I couldn't physically find the location of the plug/screw. Hopefully someone else has adjusted theirs and can post a pic of the carb body and the screw location. The air filter, spark plug, exhaust screen, and cable are all new and/or adjusted correctly. I'm sure it was staring me right in the face, but I'm just not seeing it. Thanks in advance.
    Charles
     
  2. leaver_red_jr

    leaver_red_jr LawnSite Member
    Messages: 127

    What kind of carb? If it's a rotary valve carb (likely), there's a single needle located on the axis of the valve assembly. Turn ccw (out) - rich, turn cw (in) - lean. The head of the screw is normally hidden with a bead of glue or similar to prevent tampering. This also holds the needle in place to keep adjustment, so if you make changes, you'll need to add a spring or use thread lock compound to hold the needle where you want it.
     
  3. leaver_red_jr

    leaver_red_jr LawnSite Member
    Messages: 127

    Here's the Walbro WYA service manual. Note that a spring is shown in the manual, but it does not seem to be provided on factory installed carbs.
     

    Attached Files:

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  4. Eric502

    Eric502 LawnSite Senior Member
    Male, from Kentucky
    Messages: 802

    The carb on the BL9000 is not adjustable at all to the best of my knowledge. They made it without any adjustments, which sucks. Someone on here once claimed that their dealer adjusted their carb by taking it apart, I assume they enlarged the orifice, but despite requests to elaborate the person never posted exactly what their dealer did or how. So who knows if that was even true or not.

    If it were me, I would order some Bg 44K off amazon, put a little in my 2stoke fuel and run it to see if it cleans things out. FYI I run 44k thorough all my equipment at some point each season. Be sure to check your air filter and fuel filter for any restrictions. Also check the spark plug gap.
     
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  5. OP
    OP
    crammit442

    crammit442 LawnSite Member
    Messages: 115

    You are correct about the needle screw inside the throttle shaft. On most carbs that is the LS screw and there will usually be a capped HS screw somewhere on the body of the carb. I'll get out the tach and see if minor adjustments to the screw you mention makes any difference. Thanks.
    Charles
     
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  6. OP
    OP
    crammit442

    crammit442 LawnSite Member
    Messages: 115

    Small update. There is indeed an adjustment screw in the throttle shaftThumbs Up. As usual, there's a tamper resistant plastic plug that has to come out before the screw can be adjusted. Once removed, a small flat head screwdriver is all that's needed. I didn't bother to get the tach out, but was able to pick up some WOT rpm. It's definitely NOT the HS screw, but since the LS circuit contributes to the total fuel flow, some improvement can be had while still maintaining good initial throttle response. I'll try to put the tach on it in the next few days and see exactly how many rpm it's turning. Thanks!
    Charles
     
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  7. leaver_red_jr

    leaver_red_jr LawnSite Member
    Messages: 127

    That's good news. I was able to pick up about 600 RPM on my 580BTS that way. Make sure you have a way to keep the needle from moving once it's set.
     
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  8. OP
    OP
    crammit442

    crammit442 LawnSite Member
    Messages: 115

    Fortunately the screw was quite stiff to turn. Once I get it dialed in completely, I'll probably probably just fill the hole with a dab of silicone so I can easily pick it back out if I ever need to adjust again.
    Charles
     
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  9. Eric502

    Eric502 LawnSite Senior Member
    Male, from Kentucky
    Messages: 802

    You have my attention! I'd like to adjust mine, but I am having a hard time picturing what you are describing on the BL carb.

    Basically, you are saying there is a screw on the same side as where the cable attaches inside the shaft that the cable is rotating? I see it in the diagrams that leaver red Jr posted. But I want to make sure I am understanding correctly before I go messing with it so I know where I am looking.
     
    Last edited: Jan 29, 2019
  10. OP
    OP
    crammit442

    crammit442 LawnSite Member
    Messages: 115

    If you're looking at the top of the blower (from behind), you'll see there's a black plastic squarish cover right above the carb. With that removed, you'll be almost directly above the screw location. Without having the correct anti tamper removal tool, it'll be much easier to remove the plug if you take the carb off. The rear blower housing comes off with 5 Phillips head screws. Once that's off, loosen the two hose clamps that secure the "snorkel" between the air filter and the carb and take it off. After that, 2 screws (socket head) will remove the carb. The adjustment screw is located down in the center of the throttle shaft. Because of the plug you won't be able to see the screw. The plug can be picked out with an awl, micro screwdriver, etc. Once the plug is out you'll see a small brass slotted adjustment screw. You can reassemble everything and use a long small screwdriver to adjust. You at least need to reinstall the snorkel and have the air filter assembly installed while tuning. I think it should make sense when you're actually looking at it. Just make sure to use a screwdriver that fits the adjustment screw well since the slot is shallow and brass is soft. Hope that helps.
    Charles
     
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